JP2013199025A - Image forming apparatus, image forming method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate loss when simultaneously driving adjacent nozzles, and to improve image quality.SOLUTION: An image forming apparatus includes: image data for generating an image; a head control part for transmitting a driving waveform signal for driving a nozzle for discharging ink droplets for generating the image data; a head driving part for driving the head for discharging the ink droplets from the nozzle based on the image data and the driving waveform signal; a nozzle total number detection part for detecting the total number of driven nozzles; a nozzle density detection part for detecting the ratio with which the adjacent nozzles are simultaneously driven; a compensation amount calculation part for calculating the compensation amount for compensating the jetting speed of the ink droplets based on the nozzle total number and the ratio at which the nozzles are simultaneously driven; a driving waveform data generation part for compensating the reference data being the reference for driving the head on basis of the compensation amount, and for generating the driving waveform data for driving the head; and an amplification part for driving the head based on the driving waveform data.

Description

  The present invention relates to an image forming apparatus, an image forming method, and a program.

  2. Description of the Related Art An ink jet recording apparatus including a detecting unit that detects the number of dots that eject ink from a plurality of nozzles and a unit that controls a driving voltage applied to a recording head according to the detection result of the detecting unit is generally known. ing.

  In Patent Document 1, the number of dots for ejecting ink from a plurality of nozzles for the purpose of improving the voltage fluctuation of the head driving waveform accompanying the increase in ejection nozzles and obtaining high print quality regardless of the number of driven nozzles. An ink jet recording apparatus is disclosed that includes a detecting unit that detects the above and a unit that controls a driving voltage applied to the recording head in accordance with a detection result of the detecting unit.

  In Patent Document 2, if a landing position adjustment chart in which dots are recorded by ejecting ink droplets from a plurality of nozzle holes is created and the user sets an adjustment value, it takes time to set the adjustment value. In order to solve the problem of lack of quickness, the occurrence of undershoot, overshoot, rise and / or fall delay due to fluctuations in drive voltage generated according to the number of nozzle holes ejected simultaneously from the recording head An image forming apparatus that can be appropriately and quickly suppressed is disclosed.

  However, the conventional method of controlling the driving voltage can improve the voltage fluctuation of the head driving waveform, but even if there is no fluctuation of the head driving waveform, it is attempted to eject a large number of ink droplets simultaneously from adjacent nozzles. However, there is a problem in that the image quality cannot be ensured because the ejection characteristics of each nozzle fluctuate due to pressure loss due to mechanical interference of the head structure.

  In addition, the invention disclosed in Patent Document 1 or Patent Document 2 controls a detection unit that detects the number of dots that eject ink from a plurality of nozzles, and a drive voltage that is applied to the recording head according to the detection result. However, the ejection characteristics of each nozzle will fluctuate due to pressure loss due to mechanical interference of the head structure.

  This point will be described with reference to FIG. FIG. 20 is a diagram showing the relationship between the number of drive nozzles and the ejection speed (Vj) in a conventional ink jet recording apparatus. Referring to FIG. 20, when the number of nozzles adjacent to both sides is sequentially increased from the central nozzle, even if the voltage of the driving waveform is corrected to be the same value as when driving a single nozzle, the mechanical mutual interference The problem that the drop in the injection speed (Vj) due to the residual remains is not solved.

  Accordingly, the present invention has been made in view of the above-described conventional problems, and in addition to correcting the head drive waveform due to an increase in the electrical load accompanying the increase in the number of ink ejection nozzles, when the adjacent nozzles are driven simultaneously. An object of the present invention is to provide an image forming apparatus, an image forming method, and a program capable of improving image quality by correcting pressure loss.

  In order to solve the above problem, an image forming apparatus according to the present invention is an image forming apparatus for forming an image on a recording medium, and generates image data for generating the image and the image data. A recording head controller that transmits a drive waveform signal that drives a nozzle that ejects ink droplets, and ink droplets from the nozzles based on the image data and the drive waveform signal that are transmitted from the recording head controller. A recording head driving unit that drives a recording head to be ejected, a driving nozzle total number detecting unit that detects the total number of nozzles driven based on the image data, and nozzles that are adjacently arranged based on the image data are driven simultaneously. A drive nozzle density detection unit for detecting the ratio of the nozzles, the nozzle total number detected by the drive nozzle total number detection unit, and the drive nozzle density A correction amount calculation unit that calculates a correction amount for correcting the ejection speed of the ink droplets based on the ratio at which the nozzles are simultaneously driven detected by the detection unit, and reference data that serves as a reference for driving the recording head Is corrected with the correction amount calculated by the correction amount calculation unit, and a drive waveform data generation unit that generates drive waveform data for driving the recording head, and the drive waveform generated by the drive waveform data generation unit And an amplifying unit that drives the recording head based on the data.

  According to the present invention, the density of drive nozzles indicating the degree to which adjacent nozzles are driven simultaneously is detected, and ink droplet ejection speed (Vj) and ink droplet ejection amount (Mj) are corrected according to the head structure. By doing so, an image forming apparatus, an image forming method, and a program capable of improving the image quality can be obtained.

1 is a diagram illustrating a basic configuration of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of a control unit of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a block diagram illustrating a relationship among a recording head control unit, a recording head driving unit, and a nozzle hole array of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. FIG. 4 is a timing chart illustrating a relationship among a recording head control unit, a recording head driving unit, and a nozzle hole array of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a circuit configuration for generating a signal to be supplied to a recording head driving unit of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view along the longitudinal direction of the liquid chamber of the recording head of the ink jet recording apparatus as the image forming apparatus in the embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the lateral direction of the liquid chamber of the recording head of the ink jet recording apparatus as the image forming apparatus according to the embodiment of the present invention. FIG. 2 is an explanatory plan view of a main part of a recording head of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a circuit configuration of a recording head control unit of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a relationship between a total number of detection nozzles and an ink droplet ejection speed (Vj) of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. FIG. 5 is a diagram illustrating a relationship between a correction amount (ΔVj) of an ink droplet ejection speed (Vj) and a correction rate (α) of a drive waveform of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. 6 is a flowchart for explaining the operation of the execution timing of nozzle data transfer and drive waveform correction when printing is performed with the head drive waveform of the ink jet recording apparatus as the image forming apparatus in the embodiment of the present invention. FIG. 5 is a diagram illustrating a circuit configuration that outputs a correction amount (ΔVjb) based on a maximum nozzle number detection result of image data (SD) of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. It is a figure explaining the pulse width (the number of nozzles) of image data (SD) of an ink jet recording apparatus as an image forming apparatus in an embodiment of the present invention. It is a figure which shows the correction factor characteristic of the inkjet recording device as an image forming apparatus in embodiment of this invention. FIG. 4 is a diagram illustrating a circuit configuration that outputs a correction amount (ΔVjb) based on the number of continuous nozzles and a nozzle position detection result of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. It is a figure explaining the pulse width (the number of nozzles) of image data (SD) of an ink jet recording apparatus as an image forming apparatus in an embodiment of the present invention. FIG. 3 is a diagram illustrating a relationship between a central nozzle position of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention and an ink droplet ejection speed (Vj). Regarding the relationship between the time of the ink jet recording apparatus as the image forming apparatus and the voltage of the head drive waveform (VCOM) in the embodiment of the present invention, (a) when the drive waveform data (WD) is not corrected, (b) the correction factor α It is a figure which respectively shows when it correct | amends in the voltage direction by ((alpha)> 1), and (c) It correct | amends in the time direction by the correction factor (beta) ((beta) <1). It is a figure showing the relationship between the number of drive nozzles and the injection speed (Vj) in the conventional inkjet recording device.

  Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified thru | or abbreviate | omitted suitably. The present invention corrects the drive waveform from the total number of nozzles driven at the same time, and corrects mechanical mutual interference when a larger number of nozzles are driven than when a small number of nozzles are driven. Control is performed to increase the energy amount of the drive waveform, and the drive waveform is generated by detecting the number of nozzles to be driven and the density of the nozzles at that time.

  First, an image forming apparatus according to an embodiment of the present invention will be described. FIG. 1 is a diagram illustrating a basic configuration of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. In FIG. 1, a carriage 101 is held by a guide lot 102 and scans in the main scanning direction (longitudinal direction of the pulley 104) via a pulley 104 passed between the main scanning motor 103.

  For example, a recording head 109 that discharges ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K) is mounted on the carriage 101. Ink droplets are ejected from the ejected ink ejection nozzle 110. An image is formed on the recording medium by ejecting ink droplets at a necessary position while moving the carriage 101 in the main scanning direction.

  The position information of the carriage 101 is read while moving the pattern recorded at equal intervals on the encoder sheet 105 fixed to the casing of the inkjet recording apparatus 100 by the encoder sensor 106 fixed to the carriage 101, and the counter value is added. Or it can be obtained by subtraction.

  By moving the carriage 101 in the main scanning direction and ejecting ink droplets once, an image can be formed on a band having the same width as the length of the nozzle row, and an image for one band. When the formation is completed, the sub-scanning motor 107 is driven, the recording medium is moved in the sub-scanning direction (vertical direction on the paper surface in FIG. 1), and repeated to perform the image forming operation for one band again. An image can be formed at any location on the recording medium.

  Next, the configuration of the image forming apparatus in the embodiment of the present invention will be described. FIG. 2 is a block diagram illustrating the configuration of the control unit of the ink jet recording apparatus as the image forming apparatus according to the embodiment of the present invention.

  As shown in FIG. 2, the image forming process in the embodiment of the present invention includes a host interface (host I / F (Inter / Face) that transmits a signal from a host PC (personal computer) 201 that controls the entire inkjet recording apparatus 200. )) 202, a CPU (Central Processing Unit) 203 for controlling image forming processing, a ROM (Read Only Memory) 204, a RAM (Random Access Memory) 205, a recording head control unit 206, and a main scanning control unit 207. And a sub-scanning control unit 208. These functional blocks are connected by a bus 209, and transmission / reception of signals of these functional blocks is controlled by the CPU 203.

  Specifically, firmware that performs hardware control of the inkjet recording apparatus 200 and drive waveform data that drives the recording head 1 217 to the recording head 4 220 are stored in the ROM 204, and a print job (image data) is received from the host PC 201. The CPU 203 stores the image data in the RAM 205. Note that the drive waveform data differs depending on the print mode. For example, the waveform rising speed and / or falling speed, amplitude, number of pulses, and the like are different.

  On the other hand, the carriage 210 on which the recording head 1 217 to the recording head 4 220 are mounted operates the main scanning control unit 207 based on an instruction signal from the CPU 203 and obtains a signal supply from the main scanning encoder sensor 215, The stop position of the carriage 210 is recognized, and the main scanning motor 216 is operated to move it to an arbitrary position on the recording medium (P).

  As will be described later, the recording head control unit 206 including a digital / analog converter circuit (hereinafter referred to as “DAC”), a filter circuit, and a signal amplification amplifier circuit is connected to the main scanning encoder sensor 215. In conjunction with the obtained position information of the carriage 210, image data stored in the RAM 205, drive waveform signals and control signals based on the print head drive waveform data stored in the ROM 204, the print head 1 drive unit 211, the print head 2 drive. To the recording unit 212, the recording head 3 driving unit 213, and the recording head 4 driving unit 214.

  The recording head 1 driving unit 211, the recording head 2 driving unit 212, the recording head 3 driving unit 213, and the recording head 4 driving unit 214 are based on the image data and the driving waveform signal transmitted from the recording head control unit 206. A recording head 1 217 that ejects ink droplets from the ejection nozzle row 110Y (FIG. 1), a recording head 2 218 that ejects ink droplets from the ink ejection nozzle row 110C, and a recording head 3 219 that ejects ink droplets from the ink ejection nozzle row 110M Ink droplets are ejected by driving the recording head 4220 that ejects ink droplets from the ink ejection nozzle row 110K.

  Next, the relationship between the recording head control unit, the recording head driving unit, and the nozzle hole array of the recording head of the ink jet recording apparatus as the image forming apparatus in the embodiment of the present invention will be described. FIG. 3 is a block diagram illustrating the relationship among the recording head control unit, the recording head driving unit, and the nozzle hole array of the ink jet recording apparatus as the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a timing chart illustrating the relationship among the recording head control unit, the recording head driving unit, and the nozzle hole array of the ink jet recording apparatus as the image forming apparatus according to the embodiment of the present invention.

  As described above, in the recording head control unit 206 and the recording head 1 driving unit 211 to the recording head 4 driving unit 214, as shown in FIG. Image data and a drive waveform signal are supplied to the head 4 drive unit 214, and the recording head 1 217 to the recording head 4 220 are operated to eject ink droplets from the nozzle hole arrays 110Y, 110C, 110M, and 110K. It is supposed to be.

  In this case, the operation relationship between the recording head 1 driving unit 211 to the recording head 4 driving unit 214 and the recording head 1 217 to the recording head 4 220 by the recording head control unit 206 is basically the same, and as an example the recording head A relationship among the control unit 206, the recording head 1 driving unit 211, and the recording head 1 217 will be described with reference to FIG. As shown in FIG. 3, the recording head 1 drive unit 211 includes a shift register 301, a latch 302, a gradation decoder 303, a level shifter 304, and an analog switch 305.

  The recording head 1 217 includes actuators 3Y1 to 3YN that discharge ink droplets from the nozzle holes 110 corresponding to the nozzle hole arrays 110 (FIG. 1) of the ink discharge nozzle array 110Y. Then, as shown in FIG. 3, the print head control unit 206 sends the image data SD [1: 0] and the synchronous clock signal SCK to the shift register 301, the latch 302, the gradation decoder 303, the level shifter 304, and the analog switch 305, respectively. The gradation signal MN [3: 0] and the drive waveform output signal VCOM sent from the actuators 3Y1 to 3YN corresponding to the nozzle holes 110 are transmitted.

  As a result, as shown in FIG. 4, the image data SD [1: 0] signal and the synchronization clock signal SCK are transferred from the recording head control unit 206 to the recording head 1 driving unit 211 in a serial manner, and the LT The image data SD [1: 0] is latched by a signal with a predetermined time width. The VCOM signal is output from the actuator 3Y1 by turning the analog switch 305 ON / OFF together with the gradation signal MN [3: 0] corresponding to the image data SD [1: 0] transferred serially for each nozzle hole 110. 3YN.

  Then, signals of Vout0, Vout1, Vout2, and Vout3 are formed, and “no droplet”, “small droplet”, “medium droplet”, “large” are output according to the outputs of these Vout0, Vout1, Vout2, and Vout3. A drop of ink is ejected from each nozzle hole 110. In terms of timing, as shown in FIG. 4, after serial image data is transferred with SCK, image data SD [1: 0], and LT signal, a VCOM signal and an MN signal are output as a set and output from the corresponding actuator 3Y1. 3YN operates and ink droplets are ejected from the corresponding nozzle holes 110.

  Next, the drive waveform signal VCOM will be described. FIG. 5 is a diagram illustrating a circuit configuration for generating a signal to be supplied to a recording head driving unit of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention. The drive waveform signal VCOM sequentially outputs 8-bit voltage data to the DAC 503 in accordance with the timing of driving the recording head. The DAC 503 outputs the given voltage data, for example, in an output range of 0V to 2V with a resolution of 8 bits. When the 8-bit data input step is 250 ns, when the rising time constant tr of the drive waveform (drive signal) is 5 μs and the drive voltage Vp is 30 V (full scale), the output of the DAC 503 is in increments of 20 steps. It rises to 0-2V at about 0.1V / step.

  Similarly, when the drive waveform falls, if the fall time constant tf = 10 μs, the voltage drops to 5 to 3 V in 40 steps. Further, assuming that the time required for the drive waveform (the time from the start of the rise to the end of the fall) is 50 μs, a drive waveform with a full scale of 5 V is formed in 200 steps and is repeatedly output in accordance with the drive timing of the head.

  The drive waveform output from the DAC 503 is voltage amplified in accordance with the output level of the DAC 503 in the range of 3 to 30 V (at full scale) via the voltage amplifier 504. The voltage-amplified driving waveform is given to the recording head 1 driving unit 211 via a current amplifying unit 505 including a low impedance circuit composed of a SEPP circuit (NPN transistor and PNP transistor).

  Next, an inkjet head constituting the recording head 109 (FIG. 1) of the inkjet recording apparatus will be described with reference to FIGS. 6 is a cross-sectional explanatory view along the longitudinal direction of the liquid chamber of the head, FIG. 7 is a cross-sectional explanatory view along the lateral direction of the liquid chamber of the head, and FIG.

  The inkjet head includes a flow path plate 41 formed of a single crystal silicon substrate, a vibration plate 42 bonded to the lower surface of the flow path plate 41, and a nozzle plate 43 bonded to the upper surface of the flow path plate 41. As a result, the nozzle 45 that discharges ink droplets as droplets is an ink in a pressure chamber 46 that is an ink flow path that communicates via a nozzle communication path 45a, and a common liquid chamber 48 that supplies ink to the pressure chamber 46. An ink supply path 47 serving as a fluid resistance portion communicating with the supply port 49 is formed.

  An electromechanical conversion which is a pressure generating means (actuator means) for pressurizing the ink in the pressurizing chamber 46 corresponding to each pressurizing chamber 46 on the outer surface side (the surface opposite to the liquid chamber) of the vibration plate 42. A laminated piezoelectric element 52 as an element is bonded, and the piezoelectric element 52 is bonded to a base substrate 53. Further, between the piezoelectric elements 52, support columns 54 are provided corresponding to the partition walls 41 a between the pressurizing chambers 46 and 46. Here, the piezoelectric element member is divided into comb teeth by performing slit processing by half-cut dicing, and each piezoelectric element 52 is formed as a piezoelectric element 52 and a column portion 54. The column portion 54 has the same configuration as that of the piezoelectric element 52. However, since the drive voltage is not applied, the column portion 54 is simply a column.

  Further, the outer peripheral portion of the diaphragm 42 is joined to the frame member 44 by an adhesive 50 including a gap material. The frame member 44 is formed with a recess serving as a common liquid chamber 48 and an ink supply hole (not shown) for supplying ink to the common liquid chamber 48 from the outside. The frame member 44 is formed of, for example, an epoxy resin or polyphenylene sulfite by injection molding.

  The channel plate 41 is formed by, for example, subjecting a single crystal silicon substrate having a crystal plane orientation (110) to anisotropic etching using an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH). 46, a recess or a hole serving as an ink supply path 47 is formed, but is not limited to a single crystal silicon substrate, and other stainless steel substrates, photosensitive resins, and the like can also be used.

  The vibration plate 42 is formed of a nickel metal plate, and is manufactured by, for example, an electroforming method (electroforming method). Other metal plates, resin plates, or a joining member between a metal and a resin plate, etc. It can also be used. This diaphragm 42 forms a thin part (diaphragm part) 55 for facilitating deformation and a thick part (island-like convex part) 56 for joining with the piezoelectric element 52 in a part corresponding to the pressurizing chamber 46. At the same time, a thick portion 57 is formed at a portion corresponding to the column portion 54 and a joint portion with the frame member 44, the flat surface side is adhesively joined to the flow path plate 41, and the island-like convex portion 56 is joined to the piezoelectric element 52. Further, the thick portion 57 is joined to the support portion 54 and the frame member 44 with the adhesive 50. Here, the diaphragm 42 is formed by nickel electroforming with a two-layer structure. In this case, the diaphragm portion 55 has a thickness of 3 μm and a width of 35 μm (one side).

  The nozzle plate 43 forms a nozzle 45 having a diameter of 10 to 35 μm corresponding to each pressurizing chamber 46 and is bonded to the flow path plate 41 with an adhesive. The nozzle plate 43 may be made of a metal such as stainless steel or nickel, a combination of a metal and a resin such as a polyimide resin film, silicon, or a combination thereof. Here, it forms with the Ni plating film | membrane etc. by the electroforming method. Further, the inner shape (inner shape) of the nozzle 43 is formed in a horn shape (may be a substantially columnar shape or a substantially frustum shape), and the hole diameter of the nozzle 45 is approximately 20 to 20 on the ink droplet outlet side. 35 μm. Furthermore, the nozzle pitch of each row was 150 dpi.

  Further, a water repellent treatment layer (not shown) subjected to a water repellent surface treatment is provided on the nozzle surface (surface in the ejection direction: ejection surface) of the nozzle plate 43. Examples of the water-repellent treatment layer include PTFE-Ni eutectoid plating, fluororesin electrodeposition coating, vapor-deposited fluororesin (e.g., fluorinated pitch), silicon resin / fluorine resin A water-repellent treatment film selected according to the ink physical properties such as baking after solvent application is provided to stabilize the ink droplet shape and flying characteristics so that high-quality image quality can be obtained.

  The piezoelectric element 52 includes a lead zirconate titanate (PZT) piezoelectric layer 61 having a thickness of 10 to 50 μm / layer, and an internal electrode layer 62 made of silver and palladium (AgPd) having a thickness of several μm / layer. The internal electrodes 62 are alternately stacked, and are electrically connected to the individual electrodes 63 and the common electrode 64 which are the end face electrodes (external electrodes) of the end face alternately. The pressurizing chamber 46 is contracted and expanded by expansion and contraction of the piezoelectric element 52 whose piezoelectric constant is d33. The piezoelectric element 52 expands when a drive signal is applied and is charged, and contracts in the opposite direction when the charge charged in the piezoelectric element 52 is discharged.

  Note that the end face electrode on one end face of the piezoelectric element member is divided by a dicing process by half-cut to be an individual electrode 63, and the end face electrode on the other end face is not divided by a process such as a notch and is divided by all the piezoelectric elements 52. The common electrode 64 becomes conductive.

An FPC (Flexible Printed Circuits) cable 65 is connected to the individual electrode 63 of the piezoelectric element 52 by solder bonding, ACF (anisotropic conductive film) bonding or wire bonding in order to give a drive signal. Is connected to a drive circuit (driver IC (Integrated Circuit)) for selectively applying a drive waveform to each piezoelectric element 52. The common electrode 64 is connected to the ground (GND) electrode of the FPC cable 65 by providing an electrode layer at the end of the piezoelectric element and turning it around.

  In the ink jet head configured as described above, for example, by applying a drive waveform (pulse voltage of 10 to 50 V) to the piezoelectric element 52 in accordance with a recording signal, displacement in the stacking direction occurs in the piezoelectric element 52 and vibration occurs. Ink in the pressurizing chamber 46 is pressurized through the plate 42 to increase the pressure, and ink droplets are ejected from the nozzle 45.

  Thereafter, the ink pressure in the pressurizing chamber 46 decreases with the end of ink droplet ejection, and a negative pressure is generated in the pressurizing chamber 46 due to the inertia of the ink flow and the discharge process of the drive pulse, and the ink filling process is started. Transition. At this time, ink supplied from an ink tank (not shown) flows into the common liquid chamber 48, passes through the ink supply port 49, passes through the fluid resistance portion 47 b, and is filled into the pressurizing chamber 46.

  Note that the fluid resistance portion 47b is effective in damping residual pressure vibration after ejection, but is resistant to refilling due to surface tension. By appropriately selecting the fluid resistance value of the fluid resistance portion 47b, the balance between the attenuation of the residual pressure and the refill time can be achieved, and the time (drive cycle) until the transition to the next ink droplet ejection operation can be shortened.

  By the way, in the above-described piezo (piezoelectric element) actuator type ink jet head, when the number of nozzles is increased, the driving conditions of adjacent nozzles influence each other in order to use the displacement of the piezoelectric element. The problem of mutual interference is likely to occur. For example, when vibration propagates to an adjacent pressurized liquid chamber, ink droplets are ejected from nozzles that are originally non-driven, or the pressure applied when adjacent pressurized liquid chambers are pressurized simultaneously is uneven and unstable As a result, problems such as ink droplet ejection characteristics (ink droplet ejection characteristics) differ depending on the nozzle, so-called mutual interference occurs.

  Therefore, in order to obtain the same ink droplet ejection characteristics for all nozzles in a multi-nozzle ink jet head, it is necessary to eliminate this mutual interference problem. It is not enough to solve the interference problem. That is, in the above-described conventional piezoelectric element plate in which a groove is formed and the driving unit and the non-driving unit are separated, the piezoelectric elements serving as the individual driving units are not independent. When is driven, vibration propagates to other piezoelectric elements via the piezoelectric element plate.

  In addition, in the case where the adjacent pressurized liquid chambers are communicated with each other, and the diaphragm is shared, in particular, when the piezoelectric element is driven, Vibration also propagates to the matching pressurized liquid chamber via the communication path and the diaphragm, leading to the above-described non-uniformity of the ink droplet ejection characteristics. In addition, even in the valve jet method, when a high density and high integration are achieved in order to pressurize the ink by generating a valve in the pressurized liquid chamber, the partition wall partitioning the pressurized liquid chambers However, the above-mentioned problem of mutual interference that the pressure changes in the adjacent pressurized liquid chamber due to deformation due to the applied pressure is likely to occur.

  Thus, a multi-nozzle type having a plurality of energy generating means, a plurality of pressurized liquid chambers pressurized by the plurality of energy generating means, and a plurality of nozzles communicating with the plurality of pressurized liquid chambers In the ink jet head, there is a problem that mutual interference between the nozzles occurs, and the image quality is likely to be deteriorated. The present invention has been made in view of the above points, and in particular, to reduce or prevent mutual interference in a multi-nozzle inkjet head, to prevent deterioration of ink droplet ejection characteristics, and to improve image quality. It is aimed.

  Next, the recording head control unit of the ink jet recording apparatus as the image forming apparatus in the embodiment of the present invention will be described. FIG. 9 is a diagram illustrating a circuit configuration of a recording head control unit of an ink jet recording apparatus as an image forming apparatus according to an embodiment of the present invention.

  In FIG. 9, from the image data SD, “H” data for the nozzles driven in the order of the nozzle rows and “L” data for the nozzles not driven in the order of the nozzle rows are sequentially supplied. Output from the recording head controller 206 (FIGS. 2 and 3). This image data SD is input to the drive nozzle total number detection unit 901 and the drive nozzle density detection unit 902. The drive nozzle total number detection unit 901 can detect the total number of driven nozzles by counting the number of pulses of the input “H” data.

  Further, the drive nozzle density detection unit 902 detects that the input “H” data density (“H” data is continuously detected, so that the pulse width is increased by the number of drive nozzles. The degree to which the nozzles to be driven are simultaneously driven is indicated).

  Here, the drive nozzle total number detection unit and the correction amount calculation unit 901, and the correction amount calculation units of the drive nozzle density detection unit and the correction amount calculation unit 902, based on the detected total number of nozzles and the nozzle density, The correction amounts (ΔVja) and (ΔVjb) for correcting the reduction in the ink droplet ejection speed (Vj) according to the structure are output.

  Next, the correction factor calculation unit 903 obtains digital data WD (reference waveform data) that serves as a reference of the head drive waveform to be input to the DAC 503 according to the input correction amounts (ΔVja) and (ΔVjb). A correction rate (α) for correction is output. The drive waveform data generation unit 904 outputs the waveform data α * WD corrected by the correction factor (α) to the input digital data WD.

  The DAC 503 converts the input digital waveform data WD into an analog waveform and inputs the analog waveform to the voltage amplification unit 504. The voltage amplifying unit 504 amplifies the voltage at a predetermined magnification and inputs it to the current amplifying unit 505. The current amplifying unit 505 is connected to the recording head driving unit (211 to 214) (FIG. 2), and a current necessary for driving is supplied to the head.

  Next, the relationship between the total number of nozzles detected in FIG. 9 and the ink droplet ejection speed (Vj) will be described. FIG. 10 is a diagram showing the relationship between the total number of detection nozzles and the ink droplet ejection speed (Vj) of the ink jet recording apparatus as the image forming apparatus in the embodiment of the present invention.

  In FIG. 10, the drive nozzle total number characteristic indicates that the drive waveform fluctuates due to the supply of current for the number of nozzles necessary to drive the head. Therefore, the ejection speed of ink droplets when a single nozzle is driven This shows how the ink droplet ejection speed (Vj) is reduced when is set to (Vj0).

  The drive nozzle density characteristic shows a state of reduction in the ink droplet ejection speed (Vj) that occurs even when the drive waveform fluctuation is electrically corrected. For example, when the total number of detection nozzles is 96 and the density of the drive nozzles is 16, the amount of reduction in the ink droplet ejection speed (Vj) is (ΔVja1 + ΔVjb1) from each characteristic of FIG.

  Next, the relationship between the correction amount (ΔVj) of the ink droplet ejection speed (Vj) and the correction rate α of the drive waveform will be described. FIG. 11 is a diagram illustrating the relationship between the correction amount (ΔVj) of the ink droplet ejection speed (Vj) and the correction rate (α) of the drive waveform of the ink jet recording apparatus as the image forming apparatus according to the embodiment of the present invention.

  The relationship shown in FIG. 11 is created by the D / A conversion of the reference waveform data WD by the DAC 503 in the correction rate (α) in the recording head controller 206 (FIGS. 2 and 3) described in FIG. The drive waveform after voltage amplification and current amplification corrects the reduction amount (ΔVj) of the ink droplet ejection speed (Vj) by multiplying the drive waveform in the voltage direction by several times. Vj) is a magnification that can be made equal.

  In the example of FIG. 10, since the correction amount of the ink droplet ejection speed (Vj) is (ΔVja1 + ΔVjb1), the correction rate at this time can be determined as (α1) from the characteristics of FIG. Note that (ΔVja), (ΔVjb), and (α) can be easily calculated from the ejection characteristics of the head by referring to a calculation using an approximate expression or a table prepared in advance in a memory.

  Therefore, the drive waveform data generation unit 904 shown in FIG. 9 creates (α1 * WD1) waveform data corrected in the voltage direction with respect to the reference waveform data WD1, and inputs the waveform data to the DAC 503. The drive waveform (VCOM1) is generated from the drive waveform data WD1 thus voltage-corrected through the voltage amplification unit 504 and the current amplification unit 505 after D / A conversion by the DAC 503, and the recording head drive shown in FIG. Input to the analog switch 305 (FIG. 3) of the units 211 to 214.

  Next, the timing for performing nozzle data transfer and drive waveform correction when printing with the head drive waveform (VCOM1) while scanning the carriage 210 (FIGS. 2 and 3) will be described. FIG. 12 is a flowchart for explaining the operation of nozzle data transfer and drive waveform correction timing when printing is performed with the head drive waveform of the ink jet recording apparatus as the image forming apparatus in the embodiment of the present invention.

  First, when a signal output from the main scanning encoder sensor 215 (FIG. 2) is detected in step (hereinafter referred to as “S”) 120, the recording head control unit 206 determines in S121 based on the encoder detection timing. Nozzle data for driving the head is created and transferred to the recording head driving units 211 to 214 in S122. During this time, the nozzle data transferred in S123 is latched by the latch circuit 302 (FIG. 3).

  After the nozzle data is transferred, the output from the latch circuit 302 causes the analog switch 305 to turn on only the driven nozzle in S124. At this time, the recording head control unit 206 causes the drive nozzle total number detection unit 901 to be turned on. Then, a correction factor is calculated based on the respective detection results (S128) of the drive nozzle density detection unit 902 (S129), and drive waveform data subjected to correction by the head current supply and correction by mutual interference is generated (S130). ). As the drive waveform data, a head drive waveform (VCOM) is generated via the DAC 503 (FIG. 9), the voltage amplifying unit 504, and the current amplifying unit 505 (S131) to the recording head driving units 211 to 214 (FIG. 2). Transferred (S132).

  Therefore, the head drive waveform (VCOM) is applied only to the nozzle for which the analog switch 305 is turned on (S125). Here, if the counter value of the main scanning encoder sensor 215 does not reach the predetermined printing range (S126: No), the above processing is repeatedly executed. If the counter value has reached the predetermined print range (S216: Yes), a line feed operation (sub-scan) is executed (S127), and the above-described recording head drive operation is repeated from the beginning of the line.

  Next, the relationship between the correction amount (ΔVjb) and the correction rate (α) based on the maximum nozzle number detection result of the image data (SD) will be described in detail. FIG. 13 is a diagram illustrating a circuit configuration for outputting a correction amount (ΔVjb) based on the maximum nozzle number detection result of image data (SD) of the ink jet recording apparatus as the image forming apparatus according to the embodiment of the present invention. FIG. 15 is a diagram for explaining a pulse width (number of nozzles) of image data (SD) of an ink jet recording apparatus as an image forming apparatus in an embodiment of the present invention, and FIG. 15 is an image forming apparatus in an embodiment of the present invention; It is a figure which shows the correction factor characteristic of the inkjet recording device.

  In FIG. 13, image data (serial data) (SD) is input to a maximum nozzle number detection unit that detects the maximum number of nozzles that are adjacently driven based on image data, and the maximum number of nozzles. The detection unit counts the pulse width of the input image data SD using a counter, and temporarily stores the count value. For example, in the case of the image data (SD) as shown in FIG. 14, one pulse corresponds to one nozzle, and the counter value of the image data (SD) changes from 1 → 1 → 1 → 10 → 5. At this time, the maximum nozzle number detection unit outputs a maximum counter value of 10.

  Next, the maximum value 10 of the maximum nozzle detection value is input to the correction amount calculation unit. At this time, the correction amount ΔVjb (10) is output as described with reference to FIG. The correction rate calculation unit 903 (FIG. 9) receives the correction amount ΔVja (1 + 1 + 1 + 10 + 5 = 18) from the drive nozzle total number detection unit 901 and the correction amount ΔVjb (10) from the maximum nozzle number detection unit, which are shown in FIG. Based on the correction factor characteristic, a correction factor α (18, 10) is output.

  Similarly, the drive waveform data generation unit 904 outputs α (18, 10) * WD drive waveform data, an analog waveform is output by the DAC 503, and the voltage amplification unit 504 and the current amplification unit. A drive waveform VCOM (18, 10) is generated via 505.

  Next, the relationship between the number of continuous nozzles in the image data (SD) and the correction amount (ΔVjb) based on the nozzle position detection result will be specifically described. FIG. 16 is a diagram illustrating a circuit configuration that outputs the number of continuous nozzles and the correction amount (ΔVjb) based on the nozzle position detection result of the ink jet recording apparatus as the image forming apparatus according to the embodiment of the present invention. FIG. It is a figure explaining the pulse width (the number of nozzles) of image data (SD) of an ink jet recording apparatus as an image forming apparatus in an embodiment of the invention.

  In FIG. 16, a drive nozzle density detection unit 902 (FIG. 9) includes a continuous nozzle number detection unit that detects the maximum number of nozzles that are continuously driven based on image data, and a nozzle that is continuously driven. Nozzle position detector for detecting the position (arrangement) of the image data, and image data (serial data) (SD) and serial clock (SCK) are input to each. Now, as shown in FIG. 17, the drive data for the number of adjacent nozzles of 128 nozzles is sequentially transferred to the print head drive units 211 to 214 as image data (serial data) (SD) and serial clock (SCK). In this case, the continuous nozzle number detection unit outputs a maximum value 20 as described in FIG.

  Further, the nozzle position detection unit counts the serial clock (SCK), thereby detecting that the transfer order of the maximum 20 nozzles is between the serial clock (SCK) count values 12 to 31. Therefore, it can be seen that, among the 128 nozzle arrangements, the 12th to 31st nozzles are driven simultaneously.

  The greater the number of nozzles that are driven simultaneously, the greater the influence of mutual interference. However, as explained in the section of the prior art, mutual interference is caused by the pressure applied when adjacent pressurized liquid chambers are pressurized simultaneously. This is due to non-uniformity and instability, so among the nozzle rows where the adjacent nozzle rows are arranged in the longitudinal direction (scanning direction), the closer the nozzle located near the center, the more the influence of mutual interference. It will be easy to receive.

  Next, the relationship between the center nozzle position and the ink droplet ejection speed (Vj) will be described. FIG. 18 is a diagram illustrating the relationship between the central nozzle position of the ink jet recording apparatus as the image forming apparatus according to the embodiment of the present invention and the ink droplet ejection speed (Vj).

  FIG. 18 shows the ink droplet ejection speed (Vj) when the number of nozzles driven simultaneously is (1) 1 to 16, (2) 17 to 32, (3) 33 to 64, and (4) 65 to 128. The relationship between the fluctuation and the position of the nozzle that is driven at that time (the nozzle position at the center of the nozzles that are driven simultaneously) is shown. According to this, when the nozzle data as shown in FIG. 17 is transferred, when the nozzle having a width of 20 centering on the nozzle located at the 21st position is driven simultaneously, the influence of mutual interference is the largest. From the graph of the characteristic (2) in FIG. 18, the correction amount (Vjb) of the ink droplet ejection speed (Vj) can be obtained as shown by ΔVjb (21, 20) in FIG.

  On the other hand, since the drive nozzle total number detection unit 901 (FIG. 9) detects the total number of nozzles to be driven (1 + 1 + 1 + 20 + 5 + 1 + 1 = 30), the correction amount at that time is ΔVja = ΔVja (30) Therefore, as shown in FIG. In addition, the correction rate (α) of the head drive waveform is represented by α (30, 21, 20) corresponding to the correction amount ΔVj = ΔVja (30) + ΔVjb (21, 20) of the ink droplet ejection speed (Vj). Thereafter, as shown in Fig. 9, the recording head controller 206 (Figs. 2 and 3) determines the drive waveform VCOM (from the drive waveform data of α (30, 21, 20) * WD. 30, 21, 20) can be generated and input to the recording head driving units 211 to 214.

  Next, the relationship between time and the head drive waveform will be described. FIG. 19 shows the relationship between the time of the inkjet recording apparatus as the image forming apparatus according to the embodiment of the present invention and the voltage of the head drive waveform (VCOM) when (a) the drive waveform data (WD) is not corrected. FIG. 4 is a diagram illustrating when correction is performed in the voltage direction at a correction rate α (α> 1), and when correction is performed in the time direction at a correction rate β (β <1).

  FIG. 19A shows the relationship between the time and voltage of the head drive waveform (VCOM) when the drive waveform data (WD) is not corrected. If the correction rate (α) (α> 1) is corrected in the voltage direction, the head is as shown in FIG. 19B, and has a voltage of α * Vp0 with respect to the voltage Vp0 without correction. Drive waveform. At this time, the volume change amount generated in the pressurized liquid chamber corresponding to each nozzle is α times, and the pressure loss due to the mechanical mutual interference can be corrected. As a result, the ink droplet ejection speed (Vj) of the head or Reduction of the ink droplet ejection amount (Mj) can be suppressed.

  Further, when the correction is made in the time direction at the correction rate (β) (β <1), the drive is as shown in FIG. 19C, and has a time width of β * Pw0 with respect to the time width Pw0 without correction. It becomes a waveform. At this time, the volume change time generated in the pressurized liquid chamber corresponding to each nozzle is shortened by β times, and the generated pressure can be increased, so that the pressure loss due to mechanical mutual interference can be corrected. As a result, it is possible to suppress a reduction in the ink droplet ejection speed (Vj) or the ink droplet ejection amount (Mj).

  In the above embodiment, the ink jet recording apparatus has been described. However, even in a valve jet recording apparatus, a valve is generated in the pressurized liquid chamber to pressurize the ink, so that the pressurized liquid chambers are separated from each other. Applying what has been described above in the ink jet recording apparatus because the partition wall part is deformed by the applied pressure and the pressure change is generated also in the adjacent pressurized liquid chamber, causing a problem of mechanical mutual interference. Is possible.

  Further, the operation according to the flowchart in the embodiment of the present invention shown in FIG. 12 can be executed by a program on a computer. That is, the CPU 203 in FIG. 2 that controls the operation of the ink jet recording apparatus 200 loads a program stored in a storage medium such as the ROM 204 and the RAM 205, and the processing steps of the program are sequentially executed.

  As described above, when the number of drive nozzles is increased, that is, when the electrical load is increased, the drive waveform itself is not changed compared to the drive waveform when a small number of nozzles are driven. Even if it can be corrected, the mechanical mutual interference still remains, so that the fluctuations in the ink droplet ejection speed (Vj) and the ink droplet ejection amount (Mj) remain.

  However, according to the present invention, the control is performed so that the energy amount of the drive waveform when a large number of adjacent nozzles are driven is increased rather than the drive waveform when a small number of nozzles are driven. By detecting the density of drive nozzles, which indicates the degree to which adjacent nozzles are driven simultaneously, correction of ink droplet ejection speed (Vj) and ink droplet ejection amount (Mj) according to the head structure is corrected. Image quality can be improved.

  The present invention has been described above by the preferred embodiments of the present invention. While the invention has been described with reference to specific embodiments thereof, various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the invention as defined in the claims. is there.

100, 200 Inkjet recording apparatus 101 Carriage 102 Guide lot 103 Main scanning motor 104 Pulley 105 Encoder sheet 106 Encoder sensor 107 Sub scanning motor 109 Recording head 110 Ink ejection nozzle 201 Host PC
202 Host I / F
203 CPU
204 ROM
205 RAM
206 Print Head Control Unit 207 Main Scan Control Unit 208 Sub Scan Control Unit 209 Bus 210 Carriage 211-214 Print Head Drive Units 1-4
215 Main scanning encoder sensor 216 Main scanning motor 217 to 220 Recording heads 1 to 4
Reference Signs List 301 Shift Register 302 Latch 303 Gradation Decoder 304 Level Shifter 305 Analog Switch 306 Recording Head 3Y1-3YN Nozzle Hole Array 41 Channel Plate 41a Partition Wall 42 Vibrating Plate 43 Nozzle Plate 44 Frame Member 45 Nozzle 45a Nozzle Communication Path 46 Pressure Chamber 47 Ink supply path 47a Ink supply path 47b Fluid resistance part 48 Common liquid chamber 49 Ink supply port 50 Adhesive 52 Piezoelectric element 53 Base substrate 54 Supporting part 55 Diaphragm part 56, 57 Thick part (island convex part)
503 DAC
504 Voltage amplification unit 505 Current amplification unit 50 Adhesive 61 Piezoelectric layer 62 Internal electrode layer 63 Individual electrode 64 Common electrode 65 FPC cable 901 Drive nozzle total number detection and correction amount calculation 902 Drive nozzle density detection and correction amount calculation 903 Correction rate calculation Part 904 Drive waveform data generation

Japanese Patent Laid-Open No. 05-116342 JP 2011-148287 A

Claims (5)

An image forming apparatus for forming an image on a recording medium,
A recording head controller that transmits image data for generating the image, and a drive waveform signal for driving a nozzle that discharges an ink droplet for generating the image data;
A recording head driving unit that drives a recording head that ejects ink droplets from the nozzles based on the image data and the drive waveform signal transmitted from the recording head control unit;
A drive nozzle total number detecting unit for detecting the total number of nozzles driven based on the image data;
A drive nozzle density detection unit that detects a rate at which adjacently arranged nozzles are driven simultaneously based on the image data;
A correction amount for correcting the ejection speed of the ink droplets based on the total number of nozzles detected by the total number of drive nozzles detecting unit and the ratio of the nozzles detected by the denseness detecting unit for driving nozzles being simultaneously driven. A correction amount calculation unit for calculating
A drive waveform data generation unit that corrects reference data that is a reference for driving the recording head with the correction amount calculated by the correction amount calculation unit, and generates drive waveform data that drives the recording head;
Based on the drive waveform data generated by the drive waveform data generation unit, an amplification unit that drives the recording head;
An image forming apparatus comprising:   The drive nozzle density detection unit is detected by the maximum nozzle number detection unit that detects the maximum number of nozzles that are adjacently driven based on the image data, and the maximum nozzle number detection unit. The image forming apparatus according to claim 1, further comprising: a correction amount calculation unit that calculates a correction amount for correcting the ejection speed of the ink droplet based on the maximum value.   The drive nozzle density detection unit includes a continuous nozzle number detection unit that detects a maximum value of the number of nozzles that are continuously driven based on the image data, and a nozzle position that detects a position of the nozzles that are continuously driven. A correction amount for correcting the ejection speed of the ink droplets is calculated based on the detection unit, the maximum value detected by the continuous nozzle number detection unit, and the position of the nozzle detected by the nozzle position detection unit. The image forming apparatus according to claim 1, further comprising a correction amount calculation unit. An image forming method for forming an image on a recording medium,
A step in which the recording head control unit transmits image data for forming the image and a drive waveform signal for driving a nozzle for ejecting ink droplets for forming the image data;
A recording head driving unit driving a recording head for ejecting ink droplets from the nozzles based on the image data and the drive waveform signal transmitted in the transmitting step;
A step of detecting a total number of nozzles driven based on the image data, a driving nozzle total number detection unit;
A step of detecting a density at which the adjacent nozzles are simultaneously driven based on the image data;
The correction amount calculation unit is based on the total number of nozzles detected by the step of detecting the total number of nozzles and the rate at which the nozzles detected by the step of detecting the rate at which the nozzles are simultaneously driven are simultaneously driven. Calculating a correction amount for correcting the ejection speed of the ink droplets;
A drive waveform data generation unit corrects reference data serving as a reference for driving the recording head with the correction amount calculated in the step of calculating the correction amount, and generates drive waveform data for driving the recording head. Process,
An amplifying unit driving the recording head based on the driving waveform data generated by the step of generating the driving waveform data;
An image forming method comprising: A program to be executed by a computer of an image forming apparatus that forms an image on a recording medium,
A process in which the recording head control unit transmits image data for forming the image and a drive waveform signal for driving a nozzle for discharging an ink droplet for forming the image data;
A process for driving a recording head for ejecting ink droplets from the nozzle based on the image data and the drive waveform signal transmitted by the recording head drive unit;
A process of detecting a total number of nozzles driven based on the image data by a driving nozzle total number detection unit;
A process in which the drive nozzle density detection unit detects a ratio in which adjacently arranged nozzles are driven simultaneously based on the image data;
The correction amount calculation unit is based on the total number of nozzles detected by the process of detecting the total number of nozzles and the ratio at which the nozzles detected by the process of detecting the ratio at which the nozzles are simultaneously driven are driven. A process of calculating a correction amount for correcting the ejection speed of the ink droplets;
A drive waveform data generation unit corrects reference data serving as a reference for driving the recording head with the correction amount calculated by the process of calculating the correction amount, and generates drive waveform data for driving the recording head. Processing,
A process of driving the recording head based on the drive waveform data generated by the process of generating the drive waveform data by the amplification unit;
The program characterized by including.

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